The basic two-wheeled upright hand truck has been an indispensable tool in businesses and homes for many years. Various modifications to the two-wheeled hand truck have been developed to make the hand truck more functional, such as means for securing articles to the frame of the hand truck, supplying the hand truck with powered lifting capabilities, braking and anti-tip mechanisms, or particular combinations of handle placements and positions.
One particular development has been the two-wheeled upright hand truck that is convertible to a four-wheeled push cart. One representative example of such a hand truck is found in U.S. Pat. No. 3,785,669 to Doheny, wherein a pivotable handle mounted near the top of the upright hand truck and having smaller wheels attached to the ends thereof may be pivoted relative to the frame in order to bring the handle into an upright position and the wheels into contact with the floor when the hand truck is lowered to a horizontal position. One exemplary arrangement of such a two-wheel to four-wheel conversion is shown in U.S. Pat. No. 4,921,270 issued to C. J. Schoberg. Another is shown in U.S. Pat. No. 8,100,430 issued to P. F. Meyers et al.
While these and other prior art “convertible” hand trucks are useful, there are situations where it is needed to transport a load from a first elevation to a second elevation (e.g., from the back of a truck to ground level, or from ground level to a loading platform). This is a particularly difficult, yet common occurrence (such as when moving heavy appliances from one location to another).
The hand truck arrangements of the prior art do not display this functionality of moving a load from one elevation to another.